ObjectDirectory: improve reading of shallow file

Use FileUtils.readWithRetries().

Change-Id: I5929184caca6b83a1ee87b462e541620bd68aa90

org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties

@@ -38,7 +38,7 @@ badIgnorePatternFull=File {0} line {1}: cannot parse pattern ''{2}'': {3}
 badObjectType=Bad object type: {0}
 badRef=Bad ref: {0}: {1}
 badSectionEntry=Bad section entry: {0}
-badShallowLine=Bad shallow line: {0}
+badShallowLine=Shallow file ''{0}'' has bad line: {1}
 bareRepositoryNoWorkdirAndIndex=Bare Repository has neither a working tree, nor an index
 base85invalidChar=Invalid base-85 character: 0x{0}
 base85length=Base-85 encoded data must have a length that is a multiple of 5
@@ -590,6 +590,7 @@ pushNotPermitted=push not permitted
 pushOptionsNotSupported=Push options not supported; received {0}
 rawLogMessageDoesNotParseAsLogEntry=Raw log message does not parse as log entry
 readConfigFailed=Reading config file ''{0}'' failed
+readShallowFailed=Reading shallow file ''{0}'' failed
 readFileStoreAttributesFailed=Reading FileStore attributes from user config failed
 readerIsRequired=Reader is required
 readingObjectsFromLocalRepositoryFailed=reading objects from local repository failed: {0}

org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java

@@ -618,6 +618,7 @@ public static JGitText get() {
 	/***/ public String pushOptionsNotSupported;
 	/***/ public String rawLogMessageDoesNotParseAsLogEntry;
 	/***/ public String readConfigFailed;
+	/***/ public String readShallowFailed;
 	/***/ public String readFileStoreAttributesFailed;
 	/***/ public String readerIsRequired;
 	/***/ public String readingObjectsFromLocalRepositoryFailed;

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java

@@ -567,22 +567,36 @@ public Set<ObjectId> getShallowCommits() throws IOException {
 
 		if (shallowFileSnapshot == null
 				|| shallowFileSnapshot.isModified(shallowFile)) {
-			shallowCommitsIds = new HashSet<>();
+			try {
+				shallowCommitsIds = FileUtils.readWithRetries(shallowFile,
+						f -> {
+							FileSnapshot newSnapshot = FileSnapshot.save(f);
+							HashSet<ObjectId> result = new HashSet<>();
+							try (BufferedReader reader = open(f)) {
+								String line;
+								while ((line = reader.readLine()) != null) {
+									if (!ObjectId.isId(line)) {
+										throw new IOException(
+												MessageFormat.format(JGitText
+														.get().badShallowLine,
+														f.getAbsolutePath(),
+														line));
 
-			try (BufferedReader reader = open(shallowFile)) {
+									}
-				String line;
+									result.add(ObjectId.fromString(line));
-				while ((line = reader.readLine()) != null) {
+								}
-					try {
+							}
-						shallowCommitsIds.add(ObjectId.fromString(line));
+							shallowFileSnapshot = newSnapshot;
-					} catch (IllegalArgumentException ex) {
+							return result;
-						throw new IOException(MessageFormat
+						});
-								.format(JGitText.get().badShallowLine, line),
+			} catch (IOException e) {
-								ex);
+				throw e;
-					}
+			} catch (Exception e) {
-				}
+				throw new IOException(
+						MessageFormat.format(JGitText.get().readShallowFailed,
+								shallowFile.getAbsolutePath()),
+						e);
 			}
-
-			shallowFileSnapshot = FileSnapshot.save(shallowFile);
 		}
 
 		return shallowCommitsIds;